What is the relationship between human cumulative culture and our unique social structure including cooperative breeding, pair-bonding, in-laws and cooperation with co-residing unrelated families? Contemporary hunter- gatherers provide a privileged window into the conditions for the emergence of human unmatched cultural abilities. Here I propose that the complex social networks of ancestral hunter-gatherers were a fundamental requirement for the evolution of human cumulative culture. The understanding of hunter-gatherers unique social structure provides new insights into cultural evolution and a new framework for comparative studies of humans and other primates.